Speed control devices are in common use and the purpose is to determine how much rotational speed and torque shall be communicated from an input shaft to an output shaft. These variously proposed speed drives are generally not adapted for adjustment while the gear train is operating. What is needed, is a speed control drive which is adjustable in micrometric amounts while the drive is operating and with a positive drive between the driving and driven members. For maximum utility, particularly in large presses where it is desired to commence initial operations from a very slow speed, there is needed a positive drive which is possible to adjust by micrometric increments, so that the driving member can communicate its torque and speed to the driven member by small increments and, by continuous adjustment to impart a positive drive force successively increasing the speed from the driving member through the gear train to the driven member.
Ideally, a variable speed drive should have the capability of coupling a source of power to a driven shaft or output and, by adjusting some suitable external means, determine a speed output ranging upwardly from static conditions through micrometric amounts to a preferred upper speed without power loss.
The drive should also be efficient so there is virtually no power loss, or at least minimal loss, in transferring from the power source to the driven member.
The reason these functional requirements are involved is that in many costly machines which may or may not be assembled correctly, it is desirable to go through initial machine movement only very slowly so that when such machines are first tested at low speed, damage can be minimized in the event that there is some kind of malfunctioning.
At the present time there is lacking any satisfactory speed control for carrying out these purposes; therefore, it is one of the objects of the present invention to provide a new and improved speed control drive which is externally adjustable by micrometric amounts so that a power source is adapted for driving an intended machine through an output and such an adjustment will occur by micrometric amounts whereby the speeds are adjustable through infinite increments from static up to an upper limit speed.
There is a further important feature of the present invention is that the torque communicable from the power source to the output shaft or other output means is at a high torque and selected speed.
The variable speed drive of the present invention is also adjustable and has for one of its objects adjustability of torque, speed and synchronization so that the input and output are synchronized one relatively to each other and at the preferred speed, this being the ideal situation whereby one part of a system is related to a second system both in phase and speed according to design and operational parameters.